FIG. 6 is a schematic diagram showing the structure of a conventional contactless power supply device 6. In FIG. 6, a contactless power supply device (primary side) F connected to a power panel of a power supply 9 located on the external ground side is disposed so as to oppose to a power receiving device (secondary side) G mounted on an electrically propelled vehicle, having an air gap, i.e., a clearance space, interposed between the contactless power supply device F and the power receiving device G without any physical contact when power is to be supplied. When a magnetic flux is formed at a primary coil 7 included in the power supply device F in such a disposition state, an induced electromotive force is generated at a secondary coil 8 included in the power receiving device G. Thus, the electric power is transmitted from the primary coil 7 to the secondary coil 8 in a contactless manner.
The power receiving device G is connected to an in-vehicle battery 10, for example, and the in-vehicle battery 10 is charged with the electric power transmitted in the manner as described above. An in-vehicle motor 11 is driven by the electric power stored in the battery 10. Note that, during the contactless power supply process, the power supply device F and the power receiving device G exchange necessary information between each other through a wireless communication device 12, for example.
FIG. 7 is a schematic diagram showing the internal structure of the power supply device F and the power receiving device G. In particular, FIG. 7(a) is a schematic diagram showing the internal structure of the power supply device F as seen from above, or the power receiving device G as seen from below. FIG. 7(b) is a schematic diagram showing the internal structure of the power supply device F or the power receiving device G as seen sideways.
In FIG. 7, the power supply device F includes the primary coil 7, a primary magnetic core 13, a back plate 15, a cover 16 and the like. In simple, the power receiving device G is structured symmetrically to the power supply device F, and includes the secondary coil 8, a secondary magnetic core 14, a back plate 15, a cover 16 and the like. The surface of the primary coil 7 and the primary magnetic core 13, and the surface of the secondary coil 8 and the secondary magnetic core 14 are covered and fixed by a mold resin 17 in which foam materials 18 are contained, respectively.
In other words, both the power supply device F and the power receiving device G are filled with the mold resin 17 between the back plate 15 and the cover 16, and the surface of each of the primary coil 7, the secondary coil 8, furthermore the primary magnetic core 13, and the secondary magnetic core 14 located inside is covered and fixed. The mold resin 17 is made of silicone resin, for example. By fixing the inside, the primary and secondary coils 7 and 8 are positioned and fixed, and the mechanical strength thereof is secured. In addition, the heat dissipation function is exhibited. That is, though the primary and secondary coils 7 and 8 produce heat by Joule heat as an exciting current flows, the heat is dissipated by thermal conduction of the mold resin 17, and the primary and secondary coils 7 and 8 are cooled.